Loans and Related Allowance for Credit Losses, Commitments to Lend (Details) - USD ($) $ in Millions	Mar. 31, 2022	Dec. 31, 2021
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unfunded credit commitments	$ 694,409	$ 686,721
Accounts, Notes, Loans and Financing Receivable Textual [Abstract]
Financing receivable, temporary advance arrangements	90,600
Total Commercial [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unfunded credit commitments	441,533	435,750
Commercial and industrial loans [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unfunded credit commitments	412,645	404,292
Real estate mortgage [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unfunded credit commitments	9,499	11,515
Real estate construction [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unfunded credit commitments	19,389	19,943
Total Consumer [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unfunded credit commitments	252,876	250,971
Residential mortgage - first lien [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unfunded credit commitments	32,442	32,992
Residential mortgage - junior lien [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unfunded credit commitments	25,924	27,447
Credit card [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unfunded credit commitments	135,021	130,743
Other consumer [Member]
Accounts, Notes, Loans and Financing Receivable [Line Items]
Unfunded credit commitments	59,489	59,789
International [Member] | Total Commercial [Member]
Accounts, Notes, Loans and Financing Receivable Textual [Abstract]
Letters of credit outstanding, amount	$ 1,900	$ 1,500