Investment Securities - Investment Securities by Contractual Maturity (Details) - USD ($) $ in Millions	6 Months Ended
	Jun. 30, 2022	Dec. 31, 2021
Amortized Cost
AFS securities: Amortized cost, total	$ 90,188	$ 102,515
HTM securities: Net carrying amount, total	79,477
Investment securities: amortized cost, total	169,665	182,683
Fair Value
AFS securities: Fair value, total	85,970	102,830
HTM securities: Fair value, total	71,742	79,882
Investment securities: fair value, total	$ 157,712	182,712
Annualized Average Yield
AFS securities: Annualized average yield, total (as a percent)	1.40%
HTM securities: Annualized average yield, total (as a percent)	1.80%
Investment securities: Annualized average yield, total (as a percent)	1.60%
U.S. Treasury securities
Amortized Cost
AFS securities: Amortized cost, due within 1 year	$ 10,416
AFS securities: Amortized cost, after 1 year through 5 years	43,015
AFS securities: Amortized cost, after 5 years through 10 years	3,139
AFS securities: Amortized cost, total	56,570	58,974
HTM securities: Net carrying amount, due within 1 year	3,654
HTM securities: Net carrying amount, after 1 year through 5 years	20,949
HTM securities: Net carrying amount, after 5 year through 10 years	3,968
HTM securities: Net carrying amount, after 10 years	1,562
HTM securities: Net carrying amount, total	30,133
Fair Value
AFS securities: Fair value, due within 1 year	10,300
AFS securities: Fair value, after 1 year through 5 years	41,233
AFS securities: Fair value, after 5 years through 10 years	3,125
AFS securities: Fair value, total	54,658	59,021
HTM securities: Fair value, due within 1 year	3,641
HTM securities: Fair value, after 1 year through 5 years	20,322
HTM securities: Fair value, after 5 years through 10 years	3,817
HTM securities: Fair value, after 10 years	1,313
HTM securities: Fair value, total	$ 29,093	29,454
Annualized Average Yield
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)	1.10%
AFS securities: Annualized average yield, after 5 years through 10 years (as a percent)	1.10%
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)	1.80%
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	$ 14
AFS securities: Amortized cost, after 1 year through 5 years	326
AFS securities: Amortized cost, after 5 years through 10 years	1,105
AFS securities: Amortized cost, after 10 years	22,121
AFS securities: Amortized cost, total	23,566	26,780
HTM securities: Net carrying amount, after 5 year through 10 years	425
HTM securities: Net carrying amount, after 10 years	45,713
HTM securities: Net carrying amount, total	46,138
Fair Value
AFS securities: Fair value, due within 1 year	14
AFS securities: Fair value, after 1 year through 5 years	310
AFS securities: Fair value, after 5 years through 10 years	1,051
AFS securities: Fair value, after 10 years	20,278
AFS securities: Fair value, total	21,653	26,813
HTM securities: Fair value, after 5 years through 10 years	407
HTM securities: Fair value, after 10 years	39,273
HTM securities: Fair value, total	$ 39,680	47,136
Annualized Average Yield
AFS securities: Annualized average yield, due within 1 year (as a percent)	0.70%
AFS securities: Annualized average yield, after 1 year through 5 years (as a percent)	1.20%
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)	1.80%
HTM securities: Annualized average yield, after 5 years through 10 years (as a percent)	2.10%
HTM securities: Annualized average yield, after 10 year (as a percent)	1.80%
Agency CMBS
Amortized Cost
AFS securities: Amortized cost, due within 1 year	$ 151
AFS securities: Amortized cost, after 1 year through 5 years	798
AFS securities: Amortized cost, after 5 years through 10 years	4,082
AFS securities: Amortized cost, after 10 years	1,418
AFS securities: Amortized cost, total	6,449	14,476
HTM securities: Net carrying amount, due within 1 year	105
HTM securities: Net carrying amount, after 1 year through 5 years	1,421
HTM securities: Net carrying amount, after 5 year through 10 years	405
HTM securities: Net carrying amount, after 10 years	148
HTM securities: Net carrying amount, total	2,079
Fair Value
AFS securities: Fair value, due within 1 year	151
AFS securities: Fair value, after 1 year through 5 years	760
AFS securities: Fair value, after 5 years through 10 years	3,997
AFS securities: Fair value, after 10 years	1,261
AFS securities: Fair value, total	6,169	14,676
HTM securities: Fair value, due within 1 year	104
HTM securities: Fair value, after 1 year through 5 years	1,341
HTM securities: Fair value, after 5 years through 10 years	365
HTM securities: Fair value, after 10 years	129
HTM securities: Fair value, total	$ 1,939	2,216
Annualized Average Yield
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)	2.00%
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)	1.30%
HTM securities: Annualized average yield, due within 1 year (as a percent)	1.00%
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	$ 178
HTM securities: Net carrying amount, after 1 year through 5 years	145
HTM securities: Net carrying amount, after 5 year through 10 years	751
HTM securities: Net carrying amount, after 10 years	53
HTM securities: Net carrying amount, total	1,127
Fair Value
HTM securities: Fair value, due within 1 year	177
HTM securities: Fair value, after 1 year through 5 years	138
HTM securities: Fair value, after 5 years through 10 years	665
HTM securities: Fair value, after 10 years	50
HTM securities: Fair value, total	$ 1,030	1,076
Annualized Average Yield
HTM securities: Annualized average yield, due within 1 year (as a percent)	4.10%
HTM securities: Annualized average yield, after 1 years through 5 years (as a percent)	3.60%
HTM securities: Annualized average yield, after 5 years through 10 years (as a percent)	3.60%
HTM securities: Annualized average yield, after 10 year (as a percent)	3.70%
State and municipal securities
Amortized Cost
AFS securities: Amortized cost, due within 1 year	$ 38
AFS securities: Amortized cost, after 1 year through 5 years	46
AFS securities: Amortized cost, after 5 years through 10 years	112
AFS securities: Amortized cost, after 10 years	2,126
AFS securities: Amortized cost, total	2,322	613
Fair Value
AFS securities: Fair value, due within 1 year	39
AFS securities: Fair value, after 1 year through 5 years	47
AFS securities: Fair value, after 5 years through 10 years	110
AFS securities: Fair value, after 10 years	2,048
AFS securities: Fair value, total	$ 2,244	648
Annualized Average Yield
AFS securities: Annualized average yield, due within 1 year (as a percent)	2.30%
AFS securities: Annualized average yield, after 1 year through 5 years (as a percent)	2.30%
AFS securities: Annualized average yield, after 5 years through 10 years (as a percent)	2.50%
AFS securities: Annualized average yield, after 10 years (as a percent)	3.20%
FFELP student loan ABS:
Amortized Cost
AFS securities: Amortized cost, after 1 year through 5 years	$ 127
AFS securities: Amortized cost, after 5 years through 10 years	135
AFS securities: Amortized cost, after 10 years	1,019
AFS securities: Amortized cost, total	1,281	1,672
Fair Value
AFS securities: Fair value, after 1 year through 5 years	122
AFS securities: Fair value, after 5 years through 10 years	131
AFS securities: Fair value, after 10 years	993
AFS securities: Fair value, total	$ 1,246	$ 1,672
Annualized Average Yield
AFS securities: Annualized average yield, after 1 year through 5 years (as a percent)	0.90%
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)	1.50%