Loans - Consumer Banking Portfolio by Credit Quality Indicator (Details) - USD ($) $ in Millions	Jun. 30, 2022	Dec. 31, 2021
Financing Receivable, Credit Quality Indicator [Line Items]
Total	$ 296,384	$ 277,340
Consumer Banking
Financing Receivable, Credit Quality Indicator [Line Items]
Term loans by vintage year one	20,911	38,021
Term loans by vintage year two	31,298	18,865
Term loans by vintage year three	14,669	10,789
Term loans by vintage year four	8,066	5,487
Term loans by vintage year five	3,828	2,816
Term loans by vintage after year five	2,412	1,287
Total term loans	81,184	77,265
Revolving loans	340	373
Revolving loans converted to term	7	8
Total	81,531	77,646
Auto \| Consumer Banking
Financing Receivable, Credit Quality Indicator [Line Items]
Term loans by vintage year one	20,785	37,736
Term loans by vintage year two	31,125	18,687
Term loans by vintage year three	14,569	10,615
Term loans by vintage year four	7,916	5,318
Term loans by vintage year five	3,684	2,639
Term loans by vintage after year five	1,847	784
Total term loans	79,926	75,779
Revolving loans	0	0
Revolving loans converted to term	0	0
Total	79,926	75,779
Retail banking \| Consumer Banking
Financing Receivable, Credit Quality Indicator [Line Items]
Term loans by vintage year one	126	285
Term loans by vintage year two	173	178
Term loans by vintage year three	100	174
Term loans by vintage year four	150	169
Term loans by vintage year five	144	177
Term loans by vintage after year five	565	503
Total term loans	1,258	1,486
Revolving loans	340	373
Revolving loans converted to term	7	8
Total	1,605	1,867
PPP loans	73	232
Current \| Retail banking \| Consumer Banking
Financing Receivable, Credit Quality Indicator [Line Items]
Term loans by vintage year one	126	285
Term loans by vintage year two	173	171
Term loans by vintage year three	99	172
Term loans by vintage year four	150	161
Term loans by vintage year five	141	176
Term loans by vintage after year five	555	491
Total term loans	1,244	1,456
Revolving loans	326	345
Revolving loans converted to term	6	6
Total	1,576	1,807
30-59 days \| Retail banking \| Consumer Banking
Financing Receivable, Credit Quality Indicator [Line Items]
Term loans by vintage year one	0	0
Term loans by vintage year two	0	2
Term loans by vintage year three	0	2
Term loans by vintage year four	0	7
Term loans by vintage year five	0	0
Term loans by vintage after year five	1	1
Total term loans	1	12
Revolving loans	9	23
Revolving loans converted to term	0	0
Total	10	35
60-89 days \| Retail banking \| Consumer Banking
Financing Receivable, Credit Quality Indicator [Line Items]
Term loans by vintage year one	0	0
Term loans by vintage year two	0	4
Term loans by vintage year three	0	0
Term loans by vintage year four	0	0
Term loans by vintage year five	0	0
Term loans by vintage after year five	0	2
Total term loans	0	6
Revolving loans	1	1
Revolving loans converted to term	0	0
Total	1	7
Greater than 90 days \| Retail banking \| Consumer Banking
Financing Receivable, Credit Quality Indicator [Line Items]
Term loans by vintage year one	0	0
Term loans by vintage year two	0	1
Term loans by vintage year three	1	0
Term loans by vintage year four	0	1
Term loans by vintage year five	3	1
Term loans by vintage after year five	9	9
Total term loans	13	12
Revolving loans	4	4
Revolving loans converted to term	1	2
Total	18	18
Greater than 660 \| Auto \| Consumer Banking
Financing Receivable, Credit Quality Indicator [Line Items]
Term loans by vintage year one	12,004	20,758
Term loans by vintage year two	17,114	8,630
Term loans by vintage year three	6,768	4,739
Term loans by vintage year four	3,519	2,394
Term loans by vintage year five	1,615	1,153
Term loans by vintage after year five	740	301
Total term loans	41,760	37,975
Revolving loans	0	0
Revolving loans converted to term	0	0
Total	41,760	37,975
621-660 \| Auto \| Consumer Banking
Financing Receivable, Credit Quality Indicator [Line Items]
Term loans by vintage year one	3,982	7,456
Term loans by vintage year two	6,134	3,721
Term loans by vintage year three	2,874	2,109
Term loans by vintage year four	1,566	1,084
Term loans by vintage year five	757	537
Term loans by vintage after year five	381	157
Total term loans	15,694	15,064
Revolving loans	0	0
Revolving loans converted to term	0	0
Total	15,694	15,064
620 or below \| Auto \| Consumer Banking
Financing Receivable, Credit Quality Indicator [Line Items]
Term loans by vintage year one	4,799	9,522
Term loans by vintage year two	7,877	6,336
Term loans by vintage year three	4,927	3,767
Term loans by vintage year four	2,831	1,840
Term loans by vintage year five	1,312	949
Term loans by vintage after year five	726	326
Total term loans	22,472	22,740
Revolving loans	0	0
Revolving loans converted to term	0	0
Total	$ 22,472	$ 22,740

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