Loans and Related Allowance for Credit Losses, Loans by Delinquency Status, Commercial (Details) - USD ($) $ in Millions	Mar. 31, 2022	Dec. 31, 2021	Mar. 31, 2021
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	$ 911,807	$ 895,394	$ 861,572
Nonaccrual loans	6,871	7,212
Total Commercial [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	526,714	513,120
Nonaccrual loans	1,953	2,376
Total Commercial [Member] | Current-29 days past due and still accruing [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	522,824	508,685
Total Commercial [Member] | 30-89 days past due and still accruing [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	1,670	1,824
Total Commercial [Member] | 90 days or more past due and still accruing [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	267	235
Commercial and industrial loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	362,137	350,436
Nonaccrual loans	799	980
Commercial and industrial loans [Member] | Current-29 days past due and still accruing [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	360,333	348,033
Commercial and industrial loans [Member] | 30-89 days past due and still accruing [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	819	1,217
Commercial and industrial loans [Member] | 90 days or more past due and still accruing [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	186	206
Real estate mortgage [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	129,495	127,733
Nonaccrual loans	1,033	1,235
Real estate mortgage [Member] | Current-29 days past due and still accruing [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	127,757	126,184
Real estate mortgage [Member] | 30-89 days past due and still accruing [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	625	285
Real estate mortgage [Member] | 90 days or more past due and still accruing [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	80	29
Real estate construction [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	20,613	20,092
Nonaccrual loans	4	13
Real estate construction [Member] | Current-29 days past due and still accruing [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	20,513	19,900
Real estate construction [Member] | 30-89 days past due and still accruing [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	95	179
Real estate construction [Member] | 90 days or more past due and still accruing [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	1	0
Lease financing [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	14,469	14,859
Nonaccrual loans	117	148
Lease financing [Member] | Current-29 days past due and still accruing [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	14,221	14,568
Lease financing [Member] | 30-89 days past due and still accruing [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	131	143
Lease financing [Member] | 90 days or more past due and still accruing [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Loans	$ 0	$ 0