Loans and Related Allowance for Credit Losses, 90 Days or More Past Due and Still Accruing (Details) - USD ($) $ in Millions	Mar. 31, 2022	Dec. 31, 2021
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, 90 days or more past due and still accruing	$ 4,011	$ 5,358
Non-government insured/guaranteed [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, 90 days or more past due and still accruing	676	659
Government insured or guaranteed [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, 90 days or more past due and still accruing	3,335	4,699
Total Commercial [Member] | Non-government insured/guaranteed [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, 90 days or more past due and still accruing	267	235
Commercial and industrial loans [Member] | Non-government insured/guaranteed [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, 90 days or more past due and still accruing	186	206
Real estate mortgage [Member] | Non-government insured/guaranteed [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, 90 days or more past due and still accruing	80	29
Real estate construction [Member] | Non-government insured/guaranteed [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, 90 days or more past due and still accruing	1	0
Total Consumer [Member] | Non-government insured/guaranteed [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, 90 days or more past due and still accruing	409	424
Residential mortgage - first lien [Member] | Non-government insured/guaranteed [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, 90 days or more past due and still accruing	14	37
Residential mortgage - junior lien [Member] | Non-government insured/guaranteed [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, 90 days or more past due and still accruing	6	12
Credit card [Member] | Non-government insured/guaranteed [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, 90 days or more past due and still accruing	294	269
Auto [Member] | Non-government insured/guaranteed [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, 90 days or more past due and still accruing	79	88
Other consumer [Member] | Non-government insured/guaranteed [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans, 90 days or more past due and still accruing	$ 16	$ 18