Loans and Related Allowance for Credit Losses (Nonperforming Assets) (Details) - USD ($) $ in Millions	Sep. 30, 2023	Dec. 31, 2022
Nonperforming loans, without allowance for credit losses	$ 500	$ 700
Nonperforming Loans
Nonperforming loans	2,123	1,985
OREO and foreclosed assets	35	34
Total nonperforming assets	$ 2,158	$ 2,019
Nonperforming loans to total loans	0.67%	0.61%
Nonperforming assets to total loans, OREO and foreclosed assets	0.68%	0.62%
Nonperforming assets to total assets	0.39%	0.36%
Total commercial | Nonperforming Loans
Nonperforming loans	$ 1,211	$ 858
Total consumer | Nonperforming Loans
Nonperforming loans	$ 912	$ 1,127
Unsecured Consumer Loans | Minimum
Threshold period of financing receivable past due, writeoff	120 days
Unsecured Consumer Loans | Maximum
Threshold period of financing receivable past due, writeoff	180 days