Loans and Related Allowance for Credit Losses (Nonperforming Assets) (Details) - USD ($) $ in Millions	Dec. 31, 2021	Dec. 31, 2020
Financing receivable, nonaccrual, no allowance	$ 1,000	$ 800
Nonperforming
Total nonperforming loans	2,480	2,286
OREO and Foreclosed Assets	26	51
Total nonperforming assets	$ 2,506	$ 2,337
Nonperforming loans to total loans	0.86%	0.94%
Nonperforming assets to total loans, OREO and foreclosed assets	0.87%	0.97%
Nonperforming assets to total assets	0.45%	0.50%
Minimum
Threshold period of financing receivable past due, writeoff	120 days
Maximum
Threshold period of financing receivable past due, writeoff	180 days
Commercial | Nonperforming
Total nonperforming loans	$ 1,168	$ 923
Consumer | Nonperforming
Total nonperforming loans	$ 1,312	$ 1,363