Loans and Related Allowance for Credit Losses (Financial Impact and TDRs by Concession Type) (Details) $ in Millions	3 Months Ended
	Mar. 31, 2022 USD ($) customer
Financing Receivable [Line Items]
Number of Loans | customer	2,907
Pre-TDR Amortized Cost Basis	$ 89
Post-TDR Amortized Cost Basis	79
Principal Forgiveness
Financing Receivable [Line Items]
Post-TDR Amortized Cost Basis
Rate Reduction
Financing Receivable [Line Items]
Post-TDR Amortized Cost Basis	26
Other
Financing Receivable [Line Items]
Post-TDR Amortized Cost Basis	$ 53
Total commercial
Financing Receivable [Line Items]
Number of Loans | customer	12
Pre-TDR Amortized Cost Basis	$ 53
Post-TDR Amortized Cost Basis	46
Total commercial | Principal Forgiveness
Financing Receivable [Line Items]
Post-TDR Amortized Cost Basis
Total commercial | Rate Reduction
Financing Receivable [Line Items]
Post-TDR Amortized Cost Basis
Total commercial | Other
Financing Receivable [Line Items]
Post-TDR Amortized Cost Basis	$ 46
Total consumer
Financing Receivable [Line Items]
Number of Loans | customer	2,895
Pre-TDR Amortized Cost Basis	$ 36
Post-TDR Amortized Cost Basis	33
Total consumer | Principal Forgiveness
Financing Receivable [Line Items]
Post-TDR Amortized Cost Basis
Total consumer | Rate Reduction
Financing Receivable [Line Items]
Post-TDR Amortized Cost Basis	26
Total consumer | Other
Financing Receivable [Line Items]
Post-TDR Amortized Cost Basis	$ 7