Investment Securities - Investment Securities by Contractual Maturity (Details) - USD ($) $ in Millions	9 Months Ended
	Sep. 30, 2022	Dec. 31, 2021
Amortized Cost
AFS securities: Amortized cost, total	$ 89,558	$ 102,515
HTM securities: Net carrying amount, total	77,636
Investment securities: amortized cost, total	167,194	182,683
Fair Value
AFS securities: Fair value, total	83,633	102,830
HTM securities: Fair value, total	66,393	79,882
Investment securities: fair value, total	$ 150,026	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)	1.90%
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	$ 12,692
AFS securities: Amortized cost, after 1 year through 5 years	40,430
AFS securities: Amortized cost, after 5 years through 10 years	2,991
AFS securities: Amortized cost, total	56,113	58,974
HTM securities: Net carrying amount, due within 1 year	3,429
HTM securities: Net carrying amount, after 1 year through 5 years	20,732
HTM securities: Net carrying amount, after 5 year through 10 years	3,867
HTM securities: Net carrying amount, after 10 years	1,561
HTM securities: Net carrying amount, total	29,589
Fair Value
AFS securities: Fair value, due within 1 year	12,438
AFS securities: Fair value, after 1 year through 5 years	38,199
AFS securities: Fair value, after 5 years through 10 years	2,981
AFS securities: Fair value, total	53,618	59,021
HTM securities: Fair value, due within 1 year	3,397
HTM securities: Fair value, after 1 year through 5 years	19,573
HTM securities: Fair value, after 5 years through 10 years	3,515
HTM securities: Fair value, after 10 years	1,172
HTM securities: Fair value, total	$ 27,657	29,454
Annualized Average Yield
AFS securities: Annualized average yield, due within 1 year (as a percent)	1.10%
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)	1.10%
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	$ 4
AFS securities: Amortized cost, after 1 year through 5 years	415
AFS securities: Amortized cost, after 5 years through 10 years	919
AFS securities: Amortized cost, after 10 years	22,580
AFS securities: Amortized cost, total	23,918	26,780
HTM securities: Net carrying amount, after 5 year through 10 years	399
HTM securities: Net carrying amount, after 10 years	44,546
HTM securities: Net carrying amount, total	44,945
Fair Value
AFS securities: Fair value, due within 1 year	5
AFS securities: Fair value, after 1 year through 5 years	382
AFS securities: Fair value, after 5 years through 10 years	831
AFS securities: Fair value, after 10 years	19,822
AFS securities: Fair value, total	21,040	26,813
HTM securities: Fair value, after 5 years through 10 years	362
HTM securities: Fair value, after 10 years	35,577
HTM securities: Fair value, total	$ 35,939	47,136
Annualized Average Yield
AFS securities: Annualized average yield, due within 1 year (as a percent)	0.90%
AFS securities: Annualized average yield, after 1 year through 5 years (as a percent)	1.40%
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)	1.70%
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	$ 119
AFS securities: Amortized cost, after 1 year through 5 years	854
AFS securities: Amortized cost, after 5 years through 10 years	3,856
AFS securities: Amortized cost, after 10 years	1,315
AFS securities: Amortized cost, total	6,144	14,476
HTM securities: Net carrying amount, due within 1 year	60
HTM securities: Net carrying amount, after 1 year through 5 years	1,528
HTM securities: Net carrying amount, after 5 year through 10 years	226
HTM securities: Net carrying amount, after 10 years	140
HTM securities: Net carrying amount, total	1,954
Fair Value
AFS securities: Fair value, due within 1 year	118
AFS securities: Fair value, after 1 year through 5 years	783
AFS securities: Fair value, after 5 years through 10 years	3,680
AFS securities: Fair value, after 10 years	1,117
AFS securities: Fair value, total	5,698	14,676
HTM securities: Fair value, due within 1 year	59
HTM securities: Fair value, after 1 year through 5 years	1,418
HTM securities: Fair value, after 5 years through 10 years	192
HTM securities: Fair value, after 10 years	113
HTM securities: Fair value, total	$ 1,782	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)	2.10%
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)	1.20%
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)	1.50%
HTM securities: Annualized average yield, after 10 year (as a percent)	1.50%
State and municipal securities
Amortized Cost
AFS securities: Amortized cost, due within 1 year	$ 33
AFS securities: Amortized cost, after 1 year through 5 years	28
AFS securities: Amortized cost, after 5 years through 10 years	65
AFS securities: Amortized cost, after 10 years	2,044
AFS securities: Amortized cost, total	2,170	613
Fair Value
AFS securities: Fair value, due within 1 year	34
AFS securities: Fair value, after 1 year through 5 years	29
AFS securities: Fair value, after 5 years through 10 years	62
AFS securities: Fair value, after 10 years	1,969
AFS securities: Fair value, total	$ 2,094	648
Annualized Average Yield
AFS securities: Annualized average yield, due within 1 year (as a percent)	2.50%
AFS securities: Annualized average yield, after 1 year through 5 years (as a percent)	2.60%
AFS securities: Annualized average yield, after 5 years through 10 years (as a percent)	2.60%
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	$ 122
AFS securities: Amortized cost, after 5 years through 10 years	129
AFS securities: Amortized cost, after 10 years	962
AFS securities: Amortized cost, total	1,213	1,672
Fair Value
AFS securities: Fair value, after 1 year through 5 years	118
AFS securities: Fair value, after 5 years through 10 years	124
AFS securities: Fair value, after 10 years	941
AFS securities: Fair value, total	$ 1,183	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)	1.60%
Non-agency CMBS
Amortized Cost
HTM securities: Net carrying amount, due within 1 year	$ 173
HTM securities: Net carrying amount, after 1 year through 5 years	206
HTM securities: Net carrying amount, after 5 year through 10 years	718
HTM securities: Net carrying amount, after 10 years	51
HTM securities: Net carrying amount, total	1,148
Fair Value
HTM securities: Fair value, due within 1 year	172
HTM securities: Fair value, after 1 year through 5 years	191
HTM securities: Fair value, after 5 years through 10 years	607
HTM securities: Fair value, after 10 years	45
HTM securities: Fair value, total	$ 1,015	$ 1,076
Annualized Average Yield
HTM securities: Annualized average yield, due within 1 year (as a percent)	4.00%
HTM securities: Annualized average yield, after 1 years through 5 years (as a percent)	3.90%
HTM securities: Annualized average yield, after 5 years through 10 years (as a percent)	3.70%
HTM securities: Annualized average yield, after 10 year (as a percent)	3.70%