Fair Value (Nonrecurring Fair Value Measurements) (Details) - Fair Value, Nonrecurring - USD ($) $ in Millions	3 Months Ended
	Mar. 31, 2022	Mar. 31, 2021	Dec. 31, 2021
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Nonrecurring Assets - Fair Value	$ 417		$ 457
Nonrecurring Assets - Gains (Losses)	(31)	$ (36)
Level 3 | Nonaccrual loans
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Nonrecurring Assets - Fair Value	295		348
Nonrecurring Assets - Gains (Losses)	(24)	(17)
Level 3 | Equity investments
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Nonrecurring Assets - Fair Value	112
Nonrecurring Assets - Gains (Losses)	(6)
Level 3 | OREO and foreclosed assets
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Nonrecurring Assets - Fair Value	2		6
Nonrecurring Assets - Gains (Losses)
Level 3 | Long-lived assets
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Nonrecurring Assets - Fair Value	8		$ 103
Nonrecurring Assets - Gains (Losses)	$ (1)	(2)
Level 2 | Loans held for sale
Fair Value, Assets and Liabilities Measured on Recurring and Nonrecurring Basis [Line Items]
Nonrecurring Assets - Gains (Losses)		$ (17)