Loans and Related Allowance for Credit Losses (Nonperforming Assets) (Details) - USD ($) $ in Millions		Mar. 31, 2025	Dec. 31, 2024
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans	[1]	$ 318,850	$ 316,467
Total assets		554,722	560,038
Nonperforming loans, without allowance for credit losses		600	600
Nonperforming Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans		2,292	2,326
OREO and foreclosed assets		32	31
Total assets		$ 2,324	$ 2,357
Nonperforming loans to total loans		0.72%	0.73%
Nonperforming assets to total loans, OREO and foreclosed assets		0.73%	0.74%
Nonperforming assets to total assets		0.42%	0.42%
Commercial Portfolio Segment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans		$ 219,576	$ 216,164
Commercial Portfolio Segment | Nonperforming Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans		1,467	1,462
Consumer Portfolio Segment
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans		99,274	100,303
Consumer Portfolio Segment | Nonperforming Loans
Accounts, Notes, Loans and Financing Receivable [Line Items]
Total loans		$ 825	$ 864
Unsecured Consumer Loans | Minimum
Accounts, Notes, Loans and Financing Receivable [Line Items]
Threshold period of financing receivable past due, writeoff		120 days
Unsecured Consumer Loans | Maximum
Accounts, Notes, Loans and Financing Receivable [Line Items]
Threshold period of financing receivable past due, writeoff		180 days

[1] Our consolidated assets included the following for which we have elected the fair value option: Loans held for sale of $1.0 billion, Loans held for investment of $1.1 billion and Other assets of $0.1 billion at March 31, 2025. Comparable amounts at December 31, 2024 were $0.8 billion, $1.2 billion and $0.1 billion, respectively.