Investment Securities - Investment Securities by Contractual Maturity (Details) - USD ($) $ in Millions	12 Months Ended
	Dec. 31, 2021	Dec. 31, 2020
Amortized Cost
AFS securities: Amortized cost, total	$ 102,515	$ 108,055
HTM securities: Net carrying amount, total	80,168	71,771
Investment securities: Amortized cost, total	182,683	179,826
Fair Value
AFS securities: Fair value, total	102,830	110,383
HTM securities: Fair value, total	79,882	74,420
Investment securities: Fair value, total	$ 182,712	184,803
Annualized Average Yield2
AFS securities: Annualized average yield, total (as a percent)	1.30%
HTM securities: Annualized average yield, total (as a percent)	1.80%
Investment securities: Annualized average yield, total (as a percent)	1.50%
U.S. Treasury securities
Amortized Cost
AFS securities: Amortized cost, due within 1 year	$ 8,957
AFS securities: Amortized cost, after 1 year through 5 years	41,374
AFS securities: Amortized cost, after 5 years through 10 years	8,643
AFS securities: Amortized cost, total	58,974	45,345
HTM securities: Net carrying amount, due within 1 year	4,147
HTM securities: Net carrying amount, after 1 year through 5 years	17,615
HTM securities: Net carrying amount, after 5 year through 10 years	5,328
HTM securities: Net carrying amount, after 10 years	1,563
HTM securities: Net carrying amount, total	28,653	29,346
Fair Value
AFS securities: Fair value, due within 1 year	9,017
AFS securities: Fair value, after 1 year through 5 years	41,350
AFS securities: Fair value, after 5 years through 10 years	8,654
AFS securities: Fair value, total	59,021	46,355
HTM securities: Fair value, due within 1 year	4,181
HTM securities: Fair value, after 1 year through 5 years	17,927
HTM securities: Fair value, after 5 years through 10 years	5,662
HTM securities: Fair value, after 10 years	1,684
HTM securities: Fair value, total	$ 29,454	31,239
Annualized Average Yield2
AFS securities: Annualized average yield, due within 1 year (as a percent)	1.70%
AFS securities: Annualized average yield, after 1 year through 5 years (as a percent)	1.00%
AFS securities: Annualized average yield, after 5 years through 10 years (as a percent)	1.20%
HTM securities: Annualized average yield, due within 1 year (as a percent)	1.90%
HTM securities: Annualized average yield, after 1 years through 5 years (as a percent)	1.70%
HTM securities: Annualized average yield, after 5 years through 10 years (as a percent)	2.40%
HTM securities: Annualized average yield, after 10 year (as a percent)	2.30%
U.S. agency securities
Amortized Cost
AFS securities: Amortized cost, due within 1 year	$ 1
AFS securities: Amortized cost, after 1 year through 5 years	191
AFS securities: Amortized cost, after 5 years through 10 years	1,231
AFS securities: Amortized cost, after 10 years	25,357
AFS securities: Amortized cost, total	26,780	37,389
HTM securities: Net carrying amount, after 5 year through 10 years	491
HTM securities: Net carrying amount, after 10 years	47,704
HTM securities: Net carrying amount, total	48,195	38,951
Fair Value
AFS securities: Fair value, due within 1 year	1
AFS securities: Fair value, after 1 year through 5 years	194
AFS securities: Fair value, after 5 years through 10 years	1,254
AFS securities: Fair value, after 10 years	25,364
AFS securities: Fair value, total	26,813	38,126
HTM securities: Fair value, after 5 years through 10 years	503
HTM securities: Fair value, after 10 years	46,633
HTM securities: Fair value, total	$ 47,136	39,647
Annualized Average Yield2
AFS securities: Annualized average yield, due within 1 year (as a percent)	1.20%
AFS securities: Annualized average yield, after 1 year through 5 years (as a percent)	1.60%
AFS securities: Annualized average yield, after 5 years through 10 years (as a percent)	1.80%
AFS securities: Annualized average yield, after 10 years (as a percent)	1.60%
HTM securities: Annualized average yield, after 5 years through 10 years (as a percent)	2.00%
HTM securities: Annualized average yield, after 10 year (as a percent)	1.60%
Agency CMBS
Amortized Cost
AFS securities: Amortized cost, due within 1 year	$ 226
AFS securities: Amortized cost, after 1 year through 5 years	2,562
AFS securities: Amortized cost, after 5 years through 10 years	9,072
AFS securities: Amortized cost, after 10 years	2,616
AFS securities: Amortized cost, total	14,476	19,982
HTM securities: Net carrying amount, due within 1 year	45
HTM securities: Net carrying amount, after 1 year through 5 years	1,263
HTM securities: Net carrying amount, after 5 year through 10 years	808
HTM securities: Net carrying amount, after 10 years	151
HTM securities: Net carrying amount, total	2,267	2,632
Fair Value
AFS securities: Fair value, due within 1 year	227
AFS securities: Fair value, after 1 year through 5 years	2,598
AFS securities: Fair value, after 5 years through 10 years	9,302
AFS securities: Fair value, after 10 years	2,549
AFS securities: Fair value, total	14,676	20,438
HTM securities: Fair value, due within 1 year	45
HTM securities: Fair value, after 1 year through 5 years	1,240
HTM securities: Fair value, after 5 years through 10 years	784
HTM securities: Fair value, after 10 years	147
HTM securities: Fair value, total	$ 2,216	2,634
Annualized Average Yield2
AFS securities: Annualized average yield, due within 1 year (as a percent)	1.70%
AFS securities: Annualized average yield, after 1 year through 5 years (as a percent)	1.60%
AFS securities: Annualized average yield, after 5 years through 10 years (as a percent)	1.60%
AFS securities: Annualized average yield, after 10 years (as a percent)	1.40%
HTM securities: Annualized average yield, due within 1 year (as a percent)	1.10%
HTM securities: Annualized average yield, after 1 years through 5 years (as a percent)	1.30%
HTM securities: Annualized average yield, after 5 years through 10 years (as a percent)	1.40%
HTM securities: Annualized average yield, after 10 year (as a percent)	1.50%
Non-agency CMBS
Amortized Cost
HTM securities: Net carrying amount, due within 1 year	$ 151
HTM securities: Net carrying amount, after 1 year through 5 years	109
HTM securities: Net carrying amount, after 5 year through 10 years	753
HTM securities: Net carrying amount, after 10 years	40
HTM securities: Net carrying amount, total	1,053	842
Fair Value
HTM securities: Fair value, due within 1 year	151
HTM securities: Fair value, after 1 year through 5 years	111
HTM securities: Fair value, after 5 years through 10 years	772
HTM securities: Fair value, after 10 years	42
HTM securities: Fair value, total	$ 1,076	900
Annualized Average Yield2
HTM securities: Annualized average yield, due within 1 year (as a percent)	4.50%
HTM securities: Annualized average yield, after 1 years through 5 years (as a percent)	3.10%
HTM securities: Annualized average yield, after 5 years through 10 years (as a percent)	3.50%
HTM securities: Annualized average yield, after 10 year (as a percent)	4.20%
State and municipal securities
Amortized Cost
AFS securities: Amortized cost, due within 1 year	$ 4
AFS securities: Amortized cost, after 1 year through 5 years	26
AFS securities: Amortized cost, after 5 years through 10 years	59
AFS securities: Amortized cost, after 10 years	524
AFS securities: Amortized cost, total	613	1,461
Fair Value
AFS securities: Fair value, due within 1 year	4
AFS securities: Fair value, after 1 year through 5 years	28
AFS securities: Fair value, after 5 years through 10 years	68
AFS securities: Fair value, after 10 years	548
AFS securities: Fair value, total	$ 648	1,563
Annualized Average Yield2
AFS securities: Annualized average yield, due within 1 year (as a percent)	1.80%
AFS securities: Annualized average yield, after 1 year through 5 years (as a percent)	1.90%
AFS securities: Annualized average yield, after 5 years through 10 years (as a percent)	2.10%
AFS securities: Annualized average yield, after 10 years (as a percent)	2.20%
FFELP student loan ABS
Amortized Cost
AFS securities: Amortized cost, due within 1 year	$ 31
AFS securities: Amortized cost, after 1 year through 5 years	162
AFS securities: Amortized cost, after 5 years through 10 years	143
AFS securities: Amortized cost, after 10 years	1,336
AFS securities: Amortized cost, total	1,672	1,735
Fair Value
AFS securities: Fair value, due within 1 year	30
AFS securities: Fair value, after 1 year through 5 years	158
AFS securities: Fair value, after 5 years through 10 years	139
AFS securities: Fair value, after 10 years	1,345
AFS securities: Fair value, total	$ 1,672	$ 1,716
Annualized Average Yield2
AFS securities: Annualized average yield, due within 1 year (as a percent)	0.80%
AFS securities: Annualized average yield, after 1 year through 5 years (as a percent)	0.80%
AFS securities: Annualized average yield, after 5 years through 10 years (as a percent)	0.70%
AFS securities: Annualized average yield, after 10 years (as a percent)	1.10%