Loans - Consumer, Excluding Credit Card Loan Portfolio, Residential Real Estate (Details) - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2023	Mar. 31, 2022	Dec. 31, 2022
Loans by origination year
Total retained loans	$ 1,084,850	$ 1,018,397	$ 1,089,598
Gross charge-offs by origination year
Total gross charge-offs	1,451	976
Consumer, excluding credit card
Loans by origination year
Total retained loans	300,447	296,161	300,753
Gross charge-offs by origination year
Total gross charge-offs	235	$ 204
Consumer, excluding credit card | Residential real estate
Loans by origination year
Term loans originated in 2023/2022	2,613		39,964
Term loans originated in 2022/2021	39,678		66,084
Term loans originated in 2021/2020	65,310		43,335
Term loans originated in 2020/2019	42,780		15,427
Term loans originated in 2019/2018	15,134		6,366
Term loans originated prior to 2019/2018	55,694		50,709
Revolving loans within the revolving period	5,283		5,608
Revolving loans converted to term loans	9,623		10,068
Total retained loans	$ 236,115		$ 237,561
% of 30+ days past due to total retained loans by origination year
% of 30 plus days past due to total retained loans, Term loans originated in 2023/2022	0.00%		0.08%
% of 30 plus days past due to total retained loans, Term loans originated in 2022/2021	0.06%		0.02%
% of 30 plus days past due to total retained loans, Term loans originated in 2021/2020	0.02%		0.05%
% of 30 plus days past due to total retained loans, Term loans originated in 2020/2019	0.04%		0.19%
% of 30 plus days past due to total retained loans, Term loans originated in 2019/2018	0.20%		0.42%
% of 30 plus days past due to total retained loans, Term loans originated prior to 2019/2018	1.94%		2.07%
% of 30 plus days past due to total retained loans, Revolving loans within the revolving period	0.34%		0.34%
% of 30 plus days past due to total retained loans, Revolving loans converted to term loans	4.01%		3.80%
% of 30 plus days past due to total retained loans	0.67%		0.66%
Gross charge-offs by origination year
Gross charge-offs originated in 2023	$ 0
Gross charge-offs originated in 2022	0
Gross charge-offs originated in 2021	0
Gross charge-offs originated in 2020	0
Gross charge-offs originated in 2019	0
Gross charge-offs originated prior to 2019	7
Gross charge-offs originated within the revolving period	8
Gross charge-offs originated converted to term loans	3
Total gross charge-offs	$ 18
Consumer, excluding credit card | Residential real estate | Senior lien
Gross charge-offs by origination year
Percentage of total revolving loans that are senior lien loans	37.00%
Consumer, excluding credit card | Residential real estate | Current
Loans by origination year
Term loans originated in 2023/2022	$ 2,613		$ 39,934
Term loans originated in 2022/2021	39,656		66,072
Term loans originated in 2021/2020	65,294		43,315
Term loans originated in 2020/2019	42,762		15,397
Term loans originated in 2019/2018	15,103		6,339
Term loans originated prior to 2019/2018	54,592		49,632
Revolving loans within the revolving period	5,265		5,589
Revolving loans converted to term loans	9,237		9,685
Total retained loans	234,522		235,963
Consumer, excluding credit card | Residential real estate | 30–149 days past due
Loans by origination year
Term loans originated in 2023/2022	0		29
Term loans originated in 2022/2021	21		11
Term loans originated in 2021/2020	14		14
Term loans originated in 2020/2019	13		20
Term loans originated in 2019/2018	20		20
Term loans originated prior to 2019/2018	605		597
Revolving loans within the revolving period	16		15
Revolving loans converted to term loans	216		208
Total retained loans	905		914
Consumer, excluding credit card | Residential real estate | 150 or more days past due
Loans by origination year
Term loans originated in 2023/2022	0		1
Term loans originated in 2022/2021	1		1
Term loans originated in 2021/2020	2		6
Term loans originated in 2020/2019	5		10
Term loans originated in 2019/2018	11		7
Term loans originated prior to 2019/2018	497		480
Revolving loans within the revolving period	2		4
Revolving loans converted to term loans	170		175
Total retained loans	$ 688		$ 684